Fermi-LAT detection of enhanced gamma-ray activity from the BL Lac PMN J1315-5334
ATel #17162; Janeth Valverde (Marquette University), Giovanni La Mura (INAF-O. A. Cagliari), on behalf of the Fermi Large Area Telescope Collaboration
on 25 Apr 2025; 03:32 UT
Credential Certification: Janeth Valverde (valverde@llr.in2p3.fr)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed enhanced gamma-ray activity from a source positionally consistent with PMN J1315-5334, also known as 4FGL J1315.1-5333 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 198.76742 deg, Dec. = -53.57663 deg (J2000; Xu et al. 2019, ApJS, 242, 5), and unknown redshift.
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on April 23, 2025, with a daily averaged gamma-ray flux (E>100MeV) of (0.8+/-0.3) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This value is about 25 times larger than the average flux reported in the fourth release of the Fourth Fermi-LAT catalog (4FGL-DR4; Ballet et al. 2024, arXiv:2307.12546). The corresponding photon index is 2.3+/-0.2, consistent with the 4FGL-DR4 value of 2.43+/-0.03. The Fermi-LAT Collaboration has previously reported flaring activity from this source in ATel #14929.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. Preliminary Fermi-LAT light curves for PMN J1315-5334 can be accessed via the Monitored Source List, and via the Fermi-LAT Light-Curve Repository. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Isabella Mereu (mereuisabella@gmail.com).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
